This invention is in the field of agricultural equipment and in particular the control and monitoring of the header cutting height of combines used for harvesting operations.
When harvesting with a straight cut header it is desirable to have the crop intake portion of the header held at a constant height above the ground surface. Most commonly the crop intake is a knife but other crop intake mechanisms are also known. For some crop types such as peas and beans (or other taller crops that have become lodged and are laying close to the ground surface) the knife""s vertical location must be maintained very close to the ground surface, to ensure that all the material containing seeds are picked up. At the same time it is desirable to keep the knife from moving too low and contacting the ground to avoid the likelihood of stones and soil damaging the knife or entering the combine.
For other crop types it is desirable to cut higher but at a constant monitored height above the ground surface in order to capture the seeds on the plants, which generally are located within a range of height for a particular crop variety and growing condition. It is often desirable to cut the crop as high as possible while still cutting all the plant portions that contain seeds. Cutting high increases snow catch and reduces the amount of unnecessary material passing through the combine.
The desired cutting height can thus vary from a few inches to two feet or more. Because of variations in the crop, the desired cutting height can also vary from one area of a field to another, and so it is necessary to have the height setting easy for the operator to adjust and monitor. Conventionally the header is fixedly attached to the feeder house of the combine, and the feeder house is pivotally attached to the combine body about a horizontal axis. The feeder house, and thus the header fixed thereto, are raised and lowered by hydraulic lift cylinders pushing between the combine body and the feeder house. Conventionally as well, the cutting height adjustment has been done manually by the operator who judges the cutting height visually and then adjusts the height accordingly.
Automatic header height controls are also known such as those disclosed in U.S. Pat. Nos. 4,437,295 to Rock, 5,713,190 to Vermeulen et al., 6,041,583 to Goering et al., and 6,202,395 B1 to Gramm. These devices generally include a sensor located just behind the knife, preferably as close to the knife as possible since the height at the knife is the critical distance. Means are provided to move the knife up or down in response to signals from the sensors. Many newer combines are factory equipped to receive such signals and to activate the hydraulic lift cylinders that raise and lower the feeder house in response to the signals.
These devices necessarily involve a time lag between the change in terrain which indicates an up or down movement and the actual movement. When a wheel drops into a hole, or where there is a sudden variation in terrain, this time lag can result in the knife digging into the ground, or the knife moving to high and missing crop. The operator may be required to reduce speed in uneven terrain in order to allow for this time lag.
A different approach has been taken with floating headers such as those manufactured by MacDon Industries of Winnipeg, Canada and Honey Bee Manufacturing Ltd. of Frontier, Canada which have improved ground following capabilities. These headers ride on the ground independent of the combine and can float up and down, and tilt vertically from side to side, independent from the combine""s main body, to give the header better ground following potential.
In the headers designed for improved ground following, the float mechanism generally includes an attachment of the header to the feeder house that is flexible. Right and left stops are fixed to the feeder house which move up and down with the feeder house. The header rests on these stops when the feeder house is in a raised position, but when the feeder house is lowered gauge wheels on the header contact the ground and as the feeder house continues to move lower, the header is raised off the stops and rests on the gauge wheels.
Since combine headers are very heavy, the float mechanism further includes a bias element, typically one or more springs, that exerts an upward force on the header such that only a fraction of the weight of the header is carried on the gauge wheels. When the feeder house is lowered until the header is raised off the stops on both sides, the header is in full float mode riding on the gauge wheels and is free to float up and down relative to the feeder house within a range between the stops at a lower end of the range and an upper limit defined by the mechanism. Each side of the header can move up and down independent of the opposite side within the range. On uneven terrain the header will often contact a stop on only one side, such that one end of the header rests on the stop, and the opposite end continues to float. Since the header rides on the gauge wheels the header follows the ground with the gauge wheels and there is no time lag between sensing and activation.
It is generally desired to lower the feeder housing only to the elevation required to place the header just into the full float mode, since lowering the feeder further increases the proportion of header weight carried by the gauge wheels and also may restrict the transfer of material between the header and the feeder house through the flexible connection. The combine feeder house may also contact the ground if lowered too much, resulting in dragging of soil and potential damage. In rolling terrain the operator is required to manually move the feeder house up and down to maintain this proper position.
Where the gauge wheels are fixed, the cutting height is set by the gauge wheels as the header rides along the ground on the gauge wheels with most of the header""s weight being carried by the feeder house. To adjust the cutting height it is necessary to adjust the gauge wheels up or down. As on some available headers however, the gauge wheel mounts can further include a second bias element configured such that when the feeder house is lowered just into the full float mode, the weight on the gauge wheels is minimal and the second bias element is sized so that the cutting height is substantially set by the gauge wheels. Lowering the feeder house further increases the proportion of header weight carried by the gauge wheels, and the second bias element compresses somewhat in order to develop a counteracting force to overcome the added weight. The cutting height is thus lowered by the operator on the go.
In order to smooth out small variations such as seeding ridges in the field, and to operate satisfactorily in soft ground, it is preferred to have gauge wheels with a fairly large diameter as well as width. Because of the size of the gauge wheels it is necessary to locate them behind the header, or at best under the rear portion of the header. Headers generally are oriented such that the knife at the front is the lowest point, and the bottom or table of the header slopes up towards the rear of the table. This location is substantially removed from the location of the knife, often by five feet or more.
The header thus moves up and down relative to the terrain at the gauge wheels rather than relative to the terrain at the knife, with the result that cutting height is not accurately controlled, especially on uneven or rolling terrain.
Skid pads are often used to protect the header from coming into accidental contact with the ground. When cutting very low an operator will sometimes attempt to rest the header on these skid pads continuously however the skid pads are not designed for such use and in most cases they will start to plow soil after a relatively short period of contact with the ground. There is no means provided to vary the gauged height on the go.
In addition to conventional cutting headers, where a knife severs the crop stems, there are also available stripper headers where rotating fingers strip the desired seed portions of the crop from the stems. Similar considerations apply to these stripper headers as those discussed above as, like a knife, stripper fingers must be operated low enough to catch all the seeds, and yet not in contact with the ground. Whether the crop intake is a knife or the fingers of a stripper header, the crop intake must be maintained at a constant height above the ground for best results.
It is the object of the present invention to provide a header knife height control that responds immediately to changes in ground terrain at a location in proximity to the knife.
It is a further object of the invention to provide such a header knife height control that includes a full float mode wherein the header slides along the ground on one or more float pans under the header, and wherein the distance between the bottom of the header and the float pans is adjustable and dictates the cutting height of the header.
It is a further object of the invention to provide a combine and floating header apparatus that includes a feeder house height control that controls the vertical position of the feeder house relative to the header so that the header remains in the float range as the combine moves along the ground.
The invention provides, in one aspect, a floating harvesting header apparatus including a knife attached along a front end thereof and adapted at a rear end thereof for attachment to a harvesting vehicle for movement along the ground in an operating travel direction. The apparatus comprises at least one float pan pivotally attached at a front end thereof about a substantially horizontal axis to an underside of the header at a front attachment location in proximity to the knife, the float pan extending rearward under the header. A pan actuator is attached to the float pan and to the header. The pan actuator is operative to selectively move a rear end of the float pan up and down, and operative to maintain the rear end of the float pan in a selected vertical position relative to the header such that the header slides along the ground on the float pan. A float mechanism supports the header such that the header can float up and down independently of the harvesting vehicle in a float range wherein only a portion of the header""s weight is carried on the float pan. The float pan curves down from the front attachment location and then curves upward towards the rear end of the header such that when the rear end of the float pan is raised the knife moves lower and a contact area between the float pan and the ground moves forward toward the knife.
The invention provides, in a second aspect, a combine and floating header apparatus comprising a feeder house pivotally attached at a rear end thereof to a front end of the combine about a substantially horizontal feeder axis and a feeder house actuator operative to selectively pivot the feeder house up and down about the feeder axis. A header is flexibly attached at a rear end thereof to a front end of the feeder house for cutting crop and feeding the cut crop into the feeder house and a knife is attached along a front end of the header. A right float pan is pivotally attached at a front end thereof about a substantially horizontal axis to an underside of a right portion of the header at a right front attachment location in proximity to the knife and the right float pan extends rearward under the header. A right pan actuator is attached to the right float pan and to the header. The right pan actuator is operative to selectively move a rear end of the right float pan up and down, and operative to maintain the rear end of the right float pan in a selected vertical position relative to the header such that the right portion of the header slides along the ground on the right float pan. A left float pan is pivotally attached at a front end thereof about a substantially horizontal axis to an underside of a left portion of the header at a left front attachment location in proximity to the knife and the left float pan extends rearward under the header. A left pan actuator is attached to the left float pan and to the header. The left pan actuator is operative to selectively move a rear end of the left float pan up and down, and is operative to maintain the rear end of the left float pan in a selected vertical position relative to the header such that the left portion of the header slides along the ground on the left float pan. A float mechanism supports the header such that the header can float up and down independently of the combine in a float range wherein only a portion of the header""s weight is carried on the float pans. The float pans curve down from the front attachment locations and then curve upward towards the rear end of the header such that when the rear end of the float pans are raised the knife moves lower and a contact area between the float pans and the ground moves forward toward the knife.